Quantifying the prediction of sagittal skeletal pattern using dental cast and facial profile photographs in children aged 9 to 14 years : a cross sectional study
Date of Award
Master of Science in Epidemiology & Biostatistics (MSc Epidemiology & Biostats)
Community Health Sciences
Sagittal skeletal relationship is the relationship of the upper and lower jaw in the sagittal plane. Diagnosis of the sagittal skeletal relationship is routinely done via cephalometric radiographic analysis using the ANB angle (angle between the maxillary base, nasion and mandibular base) in order to give the appropriate growth modification treatment at the right age. Cephalometric radiographs however are costly, might not be available in all dental setups especially in rural areas and expose the individual to harmful radiation exposure. Hence there is a need to explore non radiological methods to arrive at a diagnosis. Objective: To quantify prediction of sagittal skeletal pattern (ANB angle) using anteroposterior dental relationships on dental casts and facial profile photograph soft tissue analyses, adjusting for demographic, behavioral, respiratory illness and familial factors, among children aged 9 to 14 years. Methods: A cross sectional study was carried out from December 2016 to July 2017 at the Orthodontic Clinic of the Aga Khan University Hospital Karachi on a random sample of 76 patients who attended the clinic in last five years. The sagittal skeletal relationship was assessed on the cephalometric radiograph using the ANB angle. Anteroposterior dental and facial cephalometric measurements were done on their dental cast and facial profile photograph. Multiple linear regression was used to make a prediction model for ANB angle using anteroposterior dental relationships and facial profile photograph soft tissue analyses. Results: The proportion of Class 1, 11 and III malocclusion was 32.9%, 65.8% and 1.3% respectively, whereas Class 1, Class II Division 1, Class 11 Division 2 and Class III incisor relationship was found in 13.2%, 79%, 6.6% and 1.3% respectively in our study. Highest percentage of variability (47.4%) in ANB angle by the soft tissue ANB angle was observed. 54.9% of the variability in the ANB angle can be explained by overjet, soft tissue ANB' angle, lower lip to E line distance, Class II incisor relationship, history of malocclusion and thumb sucking, interaction terms between Class II incisor relationship and history of malocclusion, and history of thumb sucking and soft tissue ANB' angle. Conclusion: Sagittal skeletal relationship in an individual can be hence be predicted using the prediction equation incorporating dental and facial variables along with history of malocclusion and thumb-sucking. Thus it is a reasonably good prediction model which can be used in orthodontic clinical practice especially where cephalornetric radiograph facilities might not be available. It is however recommended that this predictive equation should be tested in different centers to assess its generalizability on a wider population.
Aga, R. F. (2017). Quantifying the prediction of sagittal skeletal pattern using dental cast and facial profile photographs in children aged 9 to 14 years : a cross sectional study (Unpublished doctoral thesis). Aga Khan University, Karachi, Pakistan.